Experiments using early sensory deprivation to alter the development of the visual and auditory systems have produced seminal work in those fields. Olfactory deprivation in the neonatal rodent has been shown to evoke dramatic anatomical and neurochemical changes in the olfactory system during development, but little is known about the corresponding functional changes during deprivation and recovery. Dr. Wachowiak and collaborators have demonstrated a transgenic mouse model in which the synaptic terminals of olfactory receptor neurons (ORNs) fluoresce when they release transmitter, permitting the in vivo imaging of ORN synaptic output in the olfactory bulb during odorant presentation. The use of these mice, therefore, provides novel opportunities to investigate the effects of sensory deprivation on the functional development of the olfactory system. The work proposed here will use these mice to study the effects of olfactory deprivation during development on synaptic transmitter release from ORNs and its presynaptic modulation by olfactory bulb circuitry, as well as the recovery from deprivation following the reopening of the naris. This research will provide new insights into the activity-dependent development and regulation of the olfactory system. [unreadable] [unreadable]